package cn.edu.scau.cmi.suwenpeng.chapter09;

public class EncryptAndDecrypt {
   String encrypt(String sourceString,String password) {
	   char[] p=password.toCharArray();
	   int n=p.length;
	   char[] c=sourceString.toCharArray();
	   int m=c.length;
	   for(int k=0;k<m;k++) {
		   int mima=c[k]+p[k%n];
		   c[k]=(char)mima;
	   }
	   return new String(c);
   }
   String decrypt(String sourceString,String password) {
	   char[] p=password.toCharArray();
	   int n=p.length;
	   char[] c=sourceString.toCharArray();
	   int m=c.length;
	   for(int k=0;k<m;k++) {
		   int mima=c[k]-p[k%n];
		   c[k]=(char)mima;
	   }
	   return new String(c);
   }

}
